Mechanical stoker.



N Patented Apr. 30, 1901. w. R. woop. 7

MECHANICAL STOKER.

(Ap alication-flled Oct. 26, 1899.)

(No Iodol.)

THE mums vzrzna n41, PHOTO-L UNITED STATES PATENT OFFICE.

WILFRED ROTHER Y WOOD, OF LONDON, ENGLAND, ASSIGNOR TO THE AMERICANSTOKER COMPANY, OF NEW YORK, N. Y.

MECHANICAL STOKER.

SPECIFICATION forming part of Letters Patent No. 672,973, dated April30, 1901.

Application filed October 26, 1899. Serial No. 734,842. (No model.)

T ctZZ whom it may concern:

Be it known that I, WILFRED ROTHERY WOOD,engineer, a citizen of the United States of America, residing at 18 Walbrook, in the cityof London,England, have invented a certain new and useful Improvement inMechanical Stokers, of which the following is a specification.

The present invention relates to detail improvements in mechanicalstoking apparatus-such, for example, as is described in my priorpatent,No. 608,8l9,dated August 9, 1898. In said patent the feed-screwis shown as having a constantly-decreasing taper and pitch from theouterto the inner end, and in stokers made in accordance with saidpatent it has been customary for the inner side walls of that portion ofthe coking or fuel chamberin which the screw rotates to leave or breakcontact with the screw at a plane drawn approximately through the axisthereof. By experiment I have found that the radial or upward feed ofthe fuel takes place almost entirely on that side of the screw on whichthe thread rises, such feed being almost tangential, and that on thedescending side the fuel at times tends to cake or accumulate and is fedforward without rising substantially, and as the pitch and taper of thescrew decrease the fuel experiences a constant-ly increasing difficultyin radial or upward movement, any tendency to which is partially impededfrom the bottom by the boss or stem of the screw, and at times so muchpower is required to drive the screw that it is sufficient to break thesame against the caked material.

According to the present invention it is proposed that the coking orfuel chamber of the magazine should only be open to a radial or upwardfeed from a point approximately on a horizontal plane with the axis ofthe screw on that side uponwhich the thread rises to a point at orslightly past that which would be formed by a plane vertically drawnthrough the axis and that the screw itself or the portion thereof withinthe coking-chamber should be a helix or spiral without a core or stemand having a gradually-decreased carrying capacity.

In order that the invention may be clearly understood, reference is madeto the accompanying drawings, which show the present invention appliedto a stoker of the class indicated; but it is to be understood that theinvention is equally applicable to stokers with varying details ofconstruction.

In said drawings, Figure 1 is a longitudinal sectional elevation of somuch of the furnace and connected parts as is necessary to showthepresent invention. Fig. 2 is-a sectional elevation, on a largerscale, on line 1 1; and Fig. 3, a like view on line 2 2. 7

As shown, the first or outer portion of feedscrew A has a constant pitchand carrying capacityand is without taper and is provided with a hollowinternally-angled boss or stem B, adapted to engage with a correspondingthe coking or fuel chamber F is shown in the form of a helix or spiral,having a constantlydecreasing carrying capacity and without a centralboss or stem, the omission of which not only gives a greater fuel-spaceand the fuel a better chance to rise, but also by doing away with thefriction between the fuel and the boss reduces very considerably thepower required to drive the screw.

To secure the radial or upward feed of the fuel, the inner side wall Gof coking or fuel chamber F, upon which the screw rises, leaves saidscrew on approximately a plane drawn horizontally through the axis ofthe screw, while the wall H leaves said screw at a point slightly pastthat which would be formed by a plane drawn vertically through thescrews axis. This construction not only prevents the screw from formingcakes or balls of fuel upon its descending side, but also provides agood bearing-surface for such screw throughout its entire length andprevents any possibility of its rising from its proper position. Thepartial pocketing or inclosing of the screw, as described, not onlyprevents it from rising, as just described, but also by supporting thecoreless spiral or helix-renders it sufficiently rigid for the purposeintended and also enables the opposite ports or twyers of thefuelchamber to be brought much closer together than is usual, thusinsuring the penetration of the draft to the center of the fuel andsecuring a very perfect cooking and combustion of the same.

What I claim is 1. In a mechanical stoker, the combination with afurnace, of a feed-screw, that portion within the fuel-chamber being inthe form of a coreless helix or spiral having a graduallydecreasingcarrying capacity and delivering radially with relation to thelongitudinal axis of the screw, substantially as described.

2. In a mechanical stoker, the combination with a furnace having acoking or fuel chamher with a delivery radially arranged with respect tothe longitudinal axis of the chamber, of a feed-screw, that portionwithin the fuelchaniber being in the form of a coreless helix or spiralhaving a gradually-decreasing carrying capacity and delivering the fuelradially into the fuel-chamber, substantially as described.

3. In a mechanical stoker, the combination with a furnace having acoking or fuel chamber with a delivery radially arranged with respect tothe longitudinal axis of the chamber, of a feed-screw the outer end ofwhich has a constant pitch and diameter and a boss or stem, and thatportion within the fuel-chamher being in the form of a coreless helix orspiral having a gradually-decreasing carrying capacity and deliveringthe fuel radially into the fuel-chamber, substantially as described.

4. In a mechanical stoker, the combination with a furnace having acoking or fuel chamber, of a horizontally-arranged feed-screw, thatportion Within the fuel-chamber being in the form of a coreless helix orspiral having a gradually-decreasing carrying capacity and deliveringupward into the fuel-chamber, the inner walls of said fuel-chamberleaving said screw at a point approximately in a horizontal plane withthe longitudinal axis of said screw at the side upon which it rises andon the descending side at a point slightly beyond that formed by avertical plane drawn through said longitudinal axis, substantially asdescribed.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

.WILFRED ROTHERY WOOD.

Witnesses:

PHILIP M. JUSTICE, ALLEN PERRY JONES.

